Braun Aktiengesellschaft

Gunther Bergk

Gerhard E Schwarz

Jochen Cimbal

The invention is directed to a method and a circuit arrangement for determining the quantity of the material cut by an electrically powered cutting tool. According to the present invention, the fluctuations of the current consumed by a drive motor are detected, filtered and evaluated. By a comparison with a reference value, it is possible to determine the soiling of the cutting tool with cut residues. The invention is particularly suitable for use in shaving apparatus.

Method of determining the quantity of the material cut by an

The invention is directed to an electronic switched-mode power supply for supplying power to an electrical energy-absorbing device from an AC or DC voltage source of different voltage levels, with a primary switched-mode flyback converter which includes a transformer having its secondary winding connected in series with the electrical energy-absorbing device and a first diode, while its primary winding is connected in series with the collector-emitter circuit of a first transistor having its base connected to the one end of the secondary winding of the transformer through a feedback capacitor, the base of the first transistor being further connected to the one pole of the input voltage source, wherein several feedback capacitors are provided which, during the transformer discharge cycle, are connected to the secondary winding of the transformer, acting as parallel-connected capacitors, and which, during the transformer charge cycle, are connected to a branch comprising the base-emitter circuit of the first transistor, acting as serially-connected capacitors. The invention is suited for use in an electric shaving apparatus.

Electronic switched-mode power supply and its use

A method of determining and displaying the charge status of a storage battery of a battery-operated appliance, such as a razor. A time-based charge status is calculated, based at least in part on the cumulative operating time of the appliance since recharging. The battery terminal voltage is also monitored. The time-based charge status is displayed until the battery voltage indicates a low voltage condition, at which point a low-charge alert indicator is displayed only if the time-based charge status is below a predetermined level (i.e., if the cumulative operating time is above a predetermined level). Methods of detecting battery aging, and for accounting for periods of excessive current flow, are included.

Method of determining and displaying battery charge status

Switched-mode power supply

Electronic switched-mode power supply

Electronic switch network part for supplying current to an accumulator

The variation of the time (t2) in which current flows from the chock (n1) of the switching power supply to the load (C3, RL), which variation is necessary for the regulation of the output voltage (Ua), is accomplished by means of a threshold switch (S) short-circuiting the coil of the choke.

Electronic switching power supply with a choke converter

An electronic switching power supply for supplying power to an electrical load from a variable voltage level AC or DC voltage source having first and second terminals, the power supply including a transformer having a primary coil and a secondary coil, a first terminal of the secondary coil being connected to the electrical load, a first transistor connected in series with the primary coil, a first diode connected in series with the secondary coil and the electrical load, a first capacitor connected between the base of the first transistor and a second terminal of the secondary coil, a second transistor, the collector-emitter line of which is connected across the voltage source, a first resistor connected between the first terminal of the secondary coil and the collector of the second transistor, a second resistor connected between the first terminal of the secondary coil and the emitter of the first transistor, and a discharge circuit connected between the first capacitor and the electrical load, whereby the first capacitor is electrically charged during a conducting phase of the first transistor, and during a subsequent blocking phase of the first transistor, the electrical load receives the charge built up in the first capacitor during the preceding conducting phase.

Electronic switching power supply

A supply circuit for supplying an electrical load with a relatively constant current from a variable voltage input source, the supply circuit including a blocking oscillator including a transformer with primary and secondary windings and a switching transistor, the load terminals of the switching transistor being connected in series with the primary winding across the voltage input source, a resistor-capacitor circuit connected between the secondary winding and a control terminal of the switching transistor, a diode connected between the secondary winding and a first terminal of the electrical load, a voltage feedback connection for applying to a first load terminal of the switching transistor a portion of the secondary winding voltage, and a reference voltage source connected to the control terminal of the switching transistor.

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Niedernhausen, Germany

Gunther Bergk